Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

191
FXUS63 KLOT 221102
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
602 AM CDT Mon Jun 22 2026

.KEY MESSAGES...

- A heightened risk for rip currents will exist at southern Lake
  Michigan beaches through tonight.

- Near to below normal temperatures will persist through the
  week with additional shower and storm chances returning in the
  mid- to late-week time frame.

&&

.DISCUSSION...
Issued at 215 AM CDT Mon Jun 22 2026

Through Tuesday:

The back edge of the rain shield associated with yesterday`s
storm system will continue to gradually peel away to the east
over the next few hours, with our forecast area likely to be
devoid of any precipitation by mid-morning. This afternoon,
clearing skies will allow for air temperatures warm into the 70s
away from the shadow of Lake Michigan, where persistent onshore
flow will keep temperatures stuck in the 60s.

A few hi-res models indicate that a few showers or sprinkles
may try to develop during peak heating this afternoon, primarily
near the I-39 corridor, where temperatures will be warmest and
some surface convergence/confluence is evident in modeled wind
fields. Confidence in diurnal cumulus growing deep enough to
support precipitation during the mid-afternoon and early evening
today isn`t particularly high given the absence of any real
large-scale forcing support and that the saturated unstable
layer depicted in hi-res model forecast soundings is somewhat
shallow and capped by a warm nose at the 700 mb level. However,
there appears to be just enough of a QPF signal to warrant the
introduction of some low-end slight chance PoPs over a portion
of interior northern Illinois during the late afternoon and
early evening for some potential isolated spits of rain.
Regardless, the vast majority of our forecast area will remain
dry today once the last of the overnight shower activity clears
the area.

Winds over Lake Michigan have been slow to come up and have,
thus far, remained a bit lower than previously forecasted. The
wave response in our nearshore waters has been more subdued as a
result, but the latest buoy observations still indicate that
waves are steadily building to levels that will create a
heightened risk of rip currents at area beaches today. Winds and
waves will then subside tonight into Tuesday as a surface high
pressure center approaches the area and eventually passes right
over us or very close by. Dry conditions are thus expected
during the daytime on Tuesday, while daytime temperature
readings will be quite similar to what they will be today.


Tuesday night through Sunday:

Late Tuesday night into Wednesday, global ensemble and
deterministic guidance remains in good agreement that an upper-
level trough will slide into the Upper Midwest, likely
accompanied by a low pressure system at the surface. Moisture
profiles should be plenty adequate to support rain showers
across the region as this system passes by, and while lapse
rates look to be lackluster on the whole, deterministic GFS and
ECMWF soundings both depict CAPE profiles with equilibrium
levels solidly above -20C that should be favorable for
thunderstorms to occur in the area as well. The greatest
coverage of showers and storms on Wednesday is favored to remain
to our north in closer proximity to the upper trough, but the
latest NBM PoPs still feature likely PoPs across the northern
third of our CWA and mid-range to upper-end chance PoPs across
the remainder of our CWA, and this looks reasonable for now
based on the latest ensemble QPF distribution.

Ensemble consistency breaks down over the latter half of the
week into the weekend, but still broadly suggests that a few
follow-up shortwave troughs could traverse the region in the
days following Wednesday. Thus, additional showery and perhaps
stormy periods could be seen going into the weekend, but
confidence in precisely when and where additional precipitation
may occur during the latter half of the week remains low at
this time. Confidence is higher in near to below normal
temperatures persisting through the entirety of this week,
though ensemble guidance does suggest that some warmer
temperatures are on the horizon for the beginning of the
following week.

Ogorek

&&

.AVIATION /12Z TAFS THROUGH 18Z TUESDAY/...
Issued at 602 AM CDT Mon Jun 22 2026

Key Messages:

- Lower MVFR CIGs quickly improving early this morning.

- Breezy northeasterly winds today, with occasional gusts around
  20 kt.

The rain has ended and CIGs are beginning to quickly improve
across the Chicago area terminals. Accordingly, we should
transition to primarily VFR conditions early this morning. The
only exception will be at GYY, where some of the low clouds may
hang on for another hour or two. Otherwise, primarily dry and
quiet weather is expected today with northeasterly winds through
the day.

KJB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Beach Hazards Statement through late tonight for ILZ006-ILZ103-
     ILZ104.

IN...Beach Hazards Statement through late tonight for INZ001-INZ002.

LM...Small Craft Advisory until 1 AM CDT Tuesday for the IL
     nearshore waters.

     Small Craft Advisory until 4 AM CDT Tuesday for the IN
     nearshore waters.

&&

$$

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